1. Field of the Invention
The present invention relates to a radiographic image capturing apparatus constituted by interconnecting a plurality of radiation detection units by means of connecting units, each of the radiation detection units being equipped with a radiation conversion panel that converts radiation into radiographic images and a panel accommodating unit accommodating the radiation conversion panel therein, as well as to a radiographic image capturing system including the radiographic image capturing apparatus and a control apparatus for controlling the radiographic image capturing apparatus.
2. Description of the Related Art
In the medical field, there have widely been used radiographic image capturing apparatus, which apply radiation to a subject and guide radiation that has passed through the subject to a radiation conversion panel, which captures a radiographic image from such radiation. Known forms of radiation conversion panels include conventional radiation film for recording a radiographic image by way of exposure, and stimulable phosphor panels for storing radiation energy representing a radiographic image in a phosphor, and reproducing the radiographic image as stimulated light by applying stimulating light to the phosphor. Radiation film with the recorded radiographic image is supplied to a developing device to develop the radiographic image, or the stimulable phosphor panel is supplied to a readout device to read the radiographic image as a visible image.
On the other hand, in an operating room or the like, for the purpose of quickly and appropriately treating patients, it is necessary to be able to read out and display a radiographic image immediately from a radiation conversion panel after the radiographic image has been captured. As a radiation conversion panel that meets such a requirement, there have been developed a radiation conversion panel of a direct conversion type having a solid-state detection element for converting radiation directly into electric signals, and a radiation conversion panel of an indirect conversion type having a scintillator for temporarily converting radiation into visible light and a solid-state detection element for converting such visible light into electric signals.
Additionally, by accommodating the aforementioned direct conversion type or indirect conversion type of radiation conversion panel in a panel accommodating unit, a radiation detection unit, also referred to as an electronic cassette, is made up. Although such an electronic cassette is higher in cost compared to radiation detection units constructed with a radiation film or a stimulable phosphor panel accommodated in the panel accommodating unit, because radiographic images of high image quality can be obtained and display of the radiographic images can be carried out rapidly, electronic cassettes have experienced widespread use in recent years.
Incidentally, as methods for capturing images with respect to a subject, there exist an ordinary image capturing technique, in which radiation having passed through a predetermined imaging region of the subject is converted into a radiographic image using a single radiation detection unit, and an elongate image capturing technique in which a radiographic image is obtained of an elongated image capturing region (e.g., the entire body of the subject) which cannot be handled by a single image (see, Japanese Laid-Open Patent Publication No. 2002-085392, Japanese Laid-Open Patent Publication No. 2000-292546, and Japanese Laid-Open Patent Publication No. 2008-017965).
In Japanese Laid-Open Patent Publication No. 2002-085392, carrying out of an elongate image capturing technique is proposed under a condition in which a plurality of stimulable phosphor sheets are partially superimposed and accommodated inside a casing. In Japanese Laid-Open Patent Publication No. 2000-292546, carrying out of an elongate image capturing technique is proposed under a condition in which a plurality of indirect conversion type radiation conversion panels are partially superimposed. In the case of Japanese Laid-Open Patent Publication No. 2002-085392 and Japanese Laid-Open Patent Publication No. 2000-292546, by image synthesis of the radiographic images obtained by each of the radiation conversion panels, an elongate image of the subject can be obtained. In Japanese Laid-Open Patent Publication No. 2008-017965, taking into consideration the fact that electronic cassettes are higher in cost and thicker than other types of radiation detection units, it is proposed to obtain a single elongate radiographic image by combining respective radiographic images after moving a single electronic cassette relatively with respect to an image capturing region of a subject, and carrying out image capturing at each of the positions to which the electronic cassette has been moved.
With the technique of Japanese Laid-Open Patent Publication No. 2002-085392, because the thickness of the stimulable phosphor sheet is comparatively thin, even when a plurality of such stimulable phosphor sheets are partially superimposed, bumps (steps) at locations (connected portions) where the sheets are superimposed are not large, and accordingly, there is little to no concern over the thickness of the casing becoming too large. However, in order to enable display of an elongate image of the subject rapidly, elongate image capturing such as that disclosed by Japanese Laid-Open Patent Publication No. 2000-292546 and Japanese Laid-Open Patent Publication No. 2008-017965 is preferred over performing elongate image capturing by means of a plurality of stimulable phosphor sheets as disclosed in Japanese Laid-Open Patent Publication No. 2002-085392.
However, with the technique disclosed in Japanese Laid-Open Patent Publication No. 2000-292546, because portions of thick electronic cassettes are superimposed, bumps (steps) at such connected locations become large, and as a result, the thickness of the casing that accommodates the plurality of electronic cassettes therein also is enlarged, leading to a concern that the system as a whole is made large in scale. In contrast, in the case elongate image capturing is used in a condition where the plurality of electronic cassettes after interconnection thereof are not accommodated in a casing, there is a fear that during image capturing the subject may experience a sense of discomfort due to the presence of such bumps.
Further, with the technique disclosed by Japanese Laid-Open Patent Publication No. 2008-017965, because exposure to radiation (image capturing) is carried out with respect to the subject at each of respective positions to which the electronic cassette is moved, although the above-mentioned problem of bumps does not occur, the subject must be maintained in the same posture over a long period of time from initiation to completion of image capturing. Further, during image capturing, if movements of the subject occur, there is a concern that, following image capturing, a breakdown in image synthesis (combining of the images) may occur.
Furthermore, electronic cassettes also comprise controllers therein for controlling the radiation conversion panels thereof. Because such controllers are structural elements that do not contribute to detection of radiation (conversion of radiation into a radiographic image), so as not to be exposed to radiation, the controllers are arranged in the electronic cassettes at a location outside of the image capturing region thereof.
However, when a plurality of electronic cassettes are interconnected such that portions of the image capturing region mutually overlap, the controller of one electronic cassette may overlap with the image capturing region of another electronic cassette, and as a result, when radiation is applied to the controllers at a time when elongate image capturing is carried out, there is a fear that the controllers will become deteriorated as a result of exposure to radiation, together with the concern that the controllers themselves may be reflected in the radiographic images.